If you look at the work of a lot of successful landscape photographers, you will probably notice that the majority of them are very good at controlling the layers of an image to create a sense of depth that draws the viewer in and encourages them to linger and explore the photo. Being able to effectively separate those layers to avoid the image becoming cluttered is a crucial skill, and this excellent video tutorial discusses how to compose your photos to do just that.
Coming to you from Andrew Marr, this great video tutorial discusses how to separate the elements in a landscape photo for greater clarity and more compelling compositions. A lot of landscape frames are rather complex, with numerous visually interesting elements, leaving the challenge to the photographer to choose a composition that places them in harmony instead of forcing them to compete for the viewer's attention, making the resulting image feel cluttered and without direction. It is a very worthwhile skill to master. Check out the video above for the full rundown from Marr.
And if you really want to dive into landscape photography, check out "Photographing The World 1: Landscape Photography and Post-Processing with Elia Locardi."